So imagine in the city your cooling system is under serious pressure. You cannot raise the temperature to 110C without raising coolant pressure (otherwise it will start boiling), So they installed 200 (2.0 BAR) radiator cap.run it cool on the highway 90-98C to get full POWER OUTPUT.īUT HERE IS A DOWNSIDE, OR A SMART BMW MOVE?: Run your engine hotter in the city or low engine loads 105-110C to get better mpg and less emissions with REDUCED POWER OUTPUT, because they think you don't need it in the city, so to save mpg. Lets say it can open it at 95C versus 105C mechanical specs. So here is what it is, Nothing crazy here- just a heater, so DME can heat it up and open it earlier than thermostat is calibrated. Since 1996 BMW introduced 105C MAP DME controlled thermostat for V8 and 97C for Inline 6 cylinders, which can be controlled by DME when needed. Obviously nothing wrong with thermostat quality, in fact its a very good quality part made by BEHR. Why I called it BMW THERMOSTAT PROBLEM? What is wrong with that simple part in BMW? It looks like a well made thermostat and lasts for a while. THIS POST AFFECTS ABSOLUTELY ALL BMW GASOLINE ENGINES AFTER 1995! M54, M62, M62TU, N62, N63, N52, N47, N63TU AND OTHERS, OR WHY IT IS A VERY GOOD IDEA TO LOWER RUNNING TEMPS!

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